Method and apparatus for recovering drill pipe from wells



g- 30, 1955 E. H. HELM METHOD AND APPARATUS FOR RECOVERING DRILL PIPE FROM WELLS 5 Sheets-Sheet 1 Filed Jan. 19, 1953 INVENTOR, fall/l h. HELK I. m

RTTOEA/EVS Aug. 30, 1955 E. H. HELM METHOD AND APPARATUS FOR RECOVERING DRILL PIPE FROM WELLS 3 Sheets-Sheet 2 Filed Jan. 19, 1953 2 -15 EG- Z INVENTOR, Ema/N h. H-ZM.

FTTQQA/EVS' Aug. 30, 1955 E. H. HELM 2,716,541 METHOD AND APP TUS FOR RECOVERING DRILL P FROM WELLS Filed Jan. 19, 1953 3 Sheets-Sheet 5 i 112L m WWA (I INVENTOR, 'fiwlA/f-l. H5414.

' BY ww United States Patent METHUD AND APPARATUS FOR RECOVERING DRILL PIPE FROM WELLS Edwin H. Helm, Odessa, Tex., assignor to The Din-Log Tubular Survey Company, Whittier, Calitl, a copartnership Application January 19, 1953, Serial No. 332,044

Claims. (Cl. 2551.8)

This invention relates to a method and apparatus for recovering drill pipe from wells that have key seated, and may be considered a further development of the subject matter disclosed in the application Serial No. 331,963, filed January 19, 1953, jointly by me and Leo A. Bell.

As set forth in the above-mentioned application, wells drilled by a rotary well drilling apparatus are seldom perfectly straight and vertical. Frequently, the well hole deviates from the vertical and may do so in a number of diiferent directions as the drilling progresses. The drilling string, although largely formed of pipe is, nevertheless, quite limber and tends to hang or be suspended in the well in a substantially straight line. Consequently, at points where the hole has deviated from the vertical the drilling string tends to hang or be disposed against the inside of the bend. As drilling proceeds the drill pipe and tool joints tend to wear a seat in the well wall at the inside of the bend which is commonly referred to as a key seat. By Way of illustration, if a 12%" bit is being used on 4 /2 drill pipe with 6% tool joints, the drill pipe tends to cut a 6 /1 hole in the well walls at the inside of the bend in the 12%" hole. If immediately above the bit there are 7" or 8" drill collars, these frequently are drawn into the bottoms of the key seats and become immovably lodged therein. This occurs most frequently when the drill string is being rapidly elevated in the hole in the course of withdrawing the drilling string to replace the drilling bit. The drill-string may also become immovably lodged in the key seat while the drilling string is being lowered into the hole. Under such circumstances, portions of the bit or drill collars may enter the top of the key seat and become stuck therein.

In accordance with the disclosure of the application above referred to, an explosive is lowered into the well on the exterior of the drill string and is positioned opposite or in the neighborhood of the key seat and exploded. Usually, at the instant of explosion the drill string is stressed in a direction that will tend to dislodge it from the key seat. In certain wells conditions may be such that it is extremely hazardous or impossible to lower a conductor cable through a long length of well hole on the outside of the drill pipe to position the explosive opposite the key seat. This may occur when the Well has deviated from the vertical in a large number of differing directions so that as the explosive is lowered by the conductor cable it winds around the drilling string. Under such circumstances it is not possible to lower the explosive to the desired depth or after the explosive has been set 01? recovery of the conductor cable may be extremely difiicult. Also, the explosive may lodge in the wall of the hole, stop on protruding ledges, or fail to go down the well where the drill pipe is leaning against the wall of the hole, thus making it impossible to lower the explosive to the desired depth.

A primary object of the present invention is to provide an improved method and apparatus wherein the explosive 2,716,541 Patented Aug. 30, 1955 and conductor cable can be lowered through the drill pipe itself to a point a short distance above the key seat and then passed to the exterior of the drill string and lowered a comparatively short distance in the open hole to the location of the key seat. After the explosive is then exploded the conductor cable can be easily recovered through the drill pipe. In this manner, that portion of the drill pipe which is above the key seat is utilized as a protector or as a means for assuring the lowering of the explosive to a point shortly above the key seat and also as a means for assuring recovery of the conductor cable.

The apparatus also contemplates providing a means by which circulation fluid may be pumped down through the drill pipe to condition the well hole prior to removal of the drill pipe following its dislodgment from the key seat.

With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

Figure l is a sectional view through a portion of a well hole illustrating drill collars of a drilling string as having been immovably lodged in a key seat and the manner in which it is ascertained where the drilling string is stuck in the well;

Fig. 2 is a similar view illustrating the free portion of the drilling string as having been detached and removed from the stuck portion thereof;

Fig. 3 is a similar view but illustrating the attachment of the apparatus embodying the present invention to the stuck portion of the drill pipe;

Fig. 4 is a vertical section through the apparatus in its extended position;

Fig. 5 is a view similar to Fig. 4, but illustrating the apparatus in its collapsed position;

Fig. 6 is a vertical section illustrating the manner in which the explosive may be lowered into position prior to its explosion;

Fig. 7 is a view illustrating the manner in which circulation may be performed prior to the withdrawal of the drilling string;

Fig. 8 is a horizontal section taken substantially upon the line 88 upon Fig. 4;

Fig. 9 is a vertical section illustrating an alternative form of construction;

Fig. 10 is a horizontal section taken substantially upon the line 10-40 upon Fig. 9; and

Fig. 11 is a vertical section illustrating the manner in which the apparatus shown in Fig. 9 can be used.

Referring to the accompaying drawings wherein similar reference characters designate similar parts throughout, it) indicates a well hole which has been drilled by a bit 11 above which there are one or more drill collars 12. These drill collars are on the lower end of a drilling string made up of sections of drill pipe 13 and 14 connected by tool joints 15.

As illustrated in a somewhat exaggerated manner, the well hole 10 has deviated from the vertical producing a bend and as drilling has progressed, the drill pipe and tool joints have worn into the wall of the hole at the inside of the bend a key seat 16. This key seat usually has a diameter approaching that of the outside diameter of the tool joints 15 but smaller than the outside diameter of the drill collars 12. Consequently, in rapidly elevating the drilling string in the well it frequently occurs that the drill collars 12 start to enter the bottom of the key seat 16 and become immovably lodged therein.

In accordance with the present invention the stuck point on the drill pipe is first ascertained. This may be ascertained in any one of several different manners, such as by lowering into the drill pipe a free pointindicator which will indicate where the drill pipe is free. Such a free point indicator has been illustrated in dotted lines on Fig. 1 consisting essentially of a strain gauge 17 preferably of the variable inductance type, the parts of which are connected respectively to upper and lower sets of belly springs 18 and 19. This strain gauge is lowered into the drill pipe on a conductor line or cable Ztl and jars and a sinker bar indicated at 21 are interposed between the conductor cable and the free point indicator. Details of such a free point indicator are shown in the applications for United States Letters Patent filed by Theodore L. Berry, Serial No. 130,535, filed December l, 1949, and So rial No. 235,533, filed July 6, 1951. Other free point indicators may be used in lieu thereof, and if none is available the approximate location of the stuck point may be approximated by putting an upward tension on the drill pipe at the surface, measuring the amount of stretch in the drill pipe, and then computing the depth of drill pipe that is free which will permit the measured stretch for the tension imposed.

in the present instance it is assumed that the free point indicator has indicated that the drill pipe is free or substantially so down to the top of the drill collars 12. it is also assumed that for one reason or another the explosive cannot be lowered into the well on the outside of the drill pipe, or that it is extremely hazardous to do so. When the free point is ascertained, a oackolf shot, i. e. a small explosive, is lowered into the drill pipe by means of the cable 2t"; and is positioned preferably within a tool joint located above the key seat. A back torque is then applied to the drill pipe, tending to unscrew it and the backoff shot is exploded. The jar of the backofi shot loosens the tool joint sutllciently so that it may be backed off or unscrewed enabling the upper section of drill pipe 14 and those sections thereabove to be detached from the lower or stuck portion of the drill pipe and to be withdrawn from the well. This leaves the stuck portion in the key seat somewhat as is depicted in Fig. 2.

A special sub of the type illustrated in Figs. 4 to 8, inclusive, is then attached to the bottom of the recovered free portion of the drill pipe and is run by means of the free portion or the drill oipe back into the hole. This sub consists of two mutually telescopic parts 22 and 23. The inner of these parts is provided with an adapter 24 at its upper end by which it is attachable to the pin section of the tool joint 35. The lower part 23 has a pin 25 which is receivable in the box section of the tool joint 15. The upper part 22 has a central bore 26 therein terminating in an angularly directed bore 27 which provides an opening from the interior of the drill pipe to the exterior thereof when the parts 22 and 23 are in extended position as illustrated in Fig. 4. At the bottom of the part 22 there is an axial bore 28 which communicates with the angularly directed bore 27 at its upper end as indicated at 25'. The lower end of the upper part 22 is externally enlarged and threaded as indicated at 30 with straight threads. This enlargement provides an external shoulder capable of abutting against a locking ring 31 which is either screwed into the upper portion of the lower part 23 or pinned in place therein, such as by the pin 32. Above the locking ring there is a hydraulic seal 33 and the top of the lower part 23 is castellated as indicated at 34 to receive splines or feathers 35 on the bottom of the adapter 24.

This special sub which is lowered into the well by the recovered portion of the drill pipe is lowered into the well in the position shown in Fig. 4. in this poistion the pin 25 may be caused to enter the box section of the tool joint 15 and to screw therein lightly. When rotary motion of the lower part 23 of the sub is arrested the upper part 22 may unscrew from the threads in the top of the lower part 23. When these threads are completely disengaged the upper part 22 can be caused to telescopically descend in the lower part 23 or into the position shown in Fig. 5. In this position the splines or feathers 35-1nay enter the tached to the stuck portion indicated at 42.

castellated portion 3d on the part 23 and the lower part 23 firmly tightened into the box section of the tool joint. When. a tight connection has been thus established between the sub and the stuck portion of the drill pipe, the upper portion 22 may then be elevated and screwed into the threads at the top of the lower part 23 so that the parts of the sub are restored to their exended position as shown in Fig. 6.

The conductor cable 20 is then made ready to lower through the recovered portion of the drill pipe. This conductor cable preferably has a bypass line 36 connected thereto to which is wired a detonating cap 37 and an explosive 38. An explosive such as Primacord is preferably used. The conductor of the conductor cable is electrically wired to the detonating cap 37. The lower end of the bypass line 36 has a weight 39 connected thereto. This weight is preferably made up of a plurality of relatively short sections flexibly connected together so that they may pass readily from the axial bore 26 through the angularly arranged bore 27. In this manner the explosive 38 may be lowered by the conductor cable 20 down through the drill pipe to a location shortly above the key seat 16 and then pass therefrom to the exterior of the drilling string and be lowered on the exterior of the drilling string to the position opposite the key seat or opposite the point where the drill collars 12 have become stuck therein. A

stress is then applied tending to dislodge the drill collars from the key seat. When the drill collars are stuck in the key seat in the position shown, the weight of the drilling string is allowed to largely rest on the stuck portion. Conversely, if the drilling string has become lodged while being lowered into the hole an upward tension would be imposed on the drilling string, tending to dislodge the stuck portion. While the stress is thus imposed the exlosive 38 is exploded. This exploding explosive either destroys the key seat or jars the drilling string sufiiciently so that it is loosened therefrom.

After the explosive has been exploded the conductor cable Ed is elevated, drawing the bypass line 36 and the weights 39 back into the drill pipe and the conductor cable and the attached parts can then be withdrawn through the drill pipe from the well. if the drill collars do not come free from the key seat and it is desired to circulate and work the pipe, the drill pipe is then rotated to unscrew the upper part 22 from the top of the lower parts 23 and the parts may be telescoped together as shown in Fig. 7. When in this position, it will be noted that the outlet from the bore 27 is disposed within the lower part 23 and that a seal is established between the seal 33 and the adapter 24. Circulation fluid may then be forced down the drilling string, passed through the sub, and be forced into the lower or previously stuck portion to condition the hole and aid in the recovery of the entire drilling string. This procedure need only be performed when it is desired to condition the hole before withdrawal of the drilling string. In many instances, it is unnecessary to perform this last step of conditioning and the drill pipe may be withdrawn as soon as it is freed by the exploding of the explosive.

In Figs. 9, l0, and ll an alternative form of construction is disclosed which in some instances is preferable. In this form of construction the special sub 44) which is attaehed to the recovered or upper portion of the drill pipe 41 is lowered into the well and is screwed into or at The sub 40 has a downwardly and laterally inclined outlet 43 for the explosive and at the top of this outlet there is formed a seat 44 for a drop valve 45. This drop valve is so designed as to enter the outlet and seat on the seat 44 and may carry a sealing ring or packing 46. The top of the drop valve is so shaped as indicated at 47 that a grab or similar retrieving tool may be lowered through the drill pipe 41 by means of a cable or line and withdraw the drop valve when desired. immediately above the seat 44 there are one or more radial passages 48 which communicate with vertical bores 49 through which circulation fluid may be discharged.

In using this form of construction after the sub 40 has been attached to the stuck portion 42, it may be desirable to attempt to circulate and work the pipe or to condition the hole before lowering the explosive. The drop valve 45 may be dropped through the drill pipe 41 and will seat on the seat 44. Circulation fluid may then be pumped down through the pipe 41 and will pass down wardly through the passages 48 and 49 in the sub. The pipe may be worked while such circulation fluid is being pumped.

When it is desired to explode the explosive opposite the key seat a grab or similar retrieving tool is lowered through the pipe 41 and is attached to the drop valve enabling the drop valve to be recovered and withdrawn. This opens the outlet 43. The explosive 50 shown as being attached to the bypass line 51 which is equipped with weights 52, can then be lowered through the drill pipe 41 and will pass out of the outlet 43 which is located a short distance above the key seat. This explosive is lowered by means of a conductor cable 53 and is detonated in the same manner as previously described. After it has exploded, the conductor cable, bypass line, and weights can ordinarily be recovered through the sub 40 and the drill pipe 41. The drop valve may or may not be again dropped through the drill pipe 41 to seat on the seat 44 to enable circulation and conditioning of the hole prior to withdrawal of the entire drill pipe.

From the above-described constructions it will be appreciated that the present invention contemplates utilizing the drill pipe as a protection for the conductor cable. Only a relatively small portion of the conductor cable need pass out of the drill pipe so as to position the explosive on the exterior of the drilling string opposite the key seat. It will be appreciated that in some instances the outlet from the bore 27 may be in close proximity to and directly against the well wall. If it is that because of this proximity that the weights 39 have not passed out of the bore 27, it is possible to rotate the upper portion of the drilling string and to unscrew the upper part 22 of the sub from the lower part 23 up to one complete revolution or the equivalent of one thread. In this manner, the bore 27 may be directed in such a direction that the weights 39 may pass therethrough and carry the explosive down on the outside of the drilling string to a position opposite the key seat.

By reason of the procedure and apparatus, recovery of the conductor line, the bypass line, and the weights is assured at all times.

Various changes may be made in the details of con struction without departing from the spirit and scope of the invention as defined by the appended claims.

I claim:

1. The method of recovering a drilling string which has become immovably lodged in a key seat which comprises ascertaining the point along the length of the drilling string where it is stuck in the well, detaching the free portion of the drilling string above the stuck point from the stuck portion and removing it from the well, attaching a sub having an opening in its wall to the free portion, running the free portion and sub back into the well and connecting the sub to the stuck portion, lowering an explosive down through the free portion and out through the opening in the sub and down on the exterior of the drilling string to a point opposite the stuck portion, exploding the explosive on the exterior of the drilling string opposite the stuck portion, and removing the stuck portion from the Well that has thus been freed by the free portion.

2. The method of recovering a drilling string which has become immovably lodged in a key seat which comprises ascertaining the point along the length of the drilling string where it is stuck in the well, detaching the free portion of the drilling string above the stuck point from the stuck portion and removing it from the well, attaching a sub having an opening in its wall to the free portion, running the free portion and sub back into the well and connecting the sub to the stuck portion, lowering an explosive down through the free portion and out through the opening in the sub and down on the exterior of the drilling string to a point opposite the stuck portion, imposing a-stress on the drilling string tending to dislodge it, exploding the explosive on the exterior of the drilling string opposite the stuck portion, and removing the stuck portion that has thus been freed by the free portion.

3. An apparatus for recovering a drilling string which has become immovably lodged in a keyseat or the like comprising a sub attachable to a free portion of a drilling string and adapted to be lowered thereby into a well, said sub being formed of two mutually telescopic parts, means on the lower of said parts by which it maybe attached to the stuck portion of the drilling string, the upper of said parts having an opening directed through a sidewall thereof, mutually engageable means on said parts for releasably holding said parts in extended position with respect to each other and wherein said opening is exposed, said means enabling the parts to be telescoped into contracted position one within the other.

4. An apparatus for recovering a drilling string which has become immovably lodged in a keyseat or the like comprising a sub attachable to a free portion of a drilling string and adapted to be lowered thereby into a well, said sub being formed of two mutually telescopic parts, means on the lower of said parts by which it may be attached to the stuck portion of the drilling string, the upper of said parts having an opening directed through a sidewall thereof, mutually engageable means on said parts for releasably holding said parts in extended position with respect to each other and wherein said opening is exposed, said means enabling the parts to be telescoped into contracted position one within the other, and means on said parts mutually engageable with each other when the parts are in contracted position for transmitting torque from the upper part to the lower part to effect a connection between the lower of said parts and the stuck portion of the drilling string.

5. An apparatus for recovering a drilling string which has become immovably lodged in a keyseat comprising a sub, said sub being formed of two mutually telescopic parts the upper of which is adapted to telescope downwardly within the lower, means for attaching the upper of said parts to a free portion of a drilling string so as to be lowered thereby into a well, means on the lower of said parts by which it may be attached to the stuck portion of a drilling string, mutually engageable threads on said parts for releasably holding the parts in extended position with respect to each other, there being an opening in the upper of said parts directed through a wall thereof which is exposed when the parts are in extended position and the end of which is disposed within the lower of said parts when the parts are in contracted position, there being a bore through the lower portion of the upper part communicating with said opening, and means on said parts mutually engageable with each other when the parts are in contracted position for transmitting torque from the upper part to the lower part to effect a connection between the lower of said parts and the stuck portion of the drilling string.

References Cited in the file of this patent UNITED STATES PATENTS 2,176,375 McClinton Oct. 17, 1939 2,305,261 Kinley Dec. 15, 1942 2,414,349 Alexander Jan. 14, 1947 2,510,386 Denning et a1 June 6, 1950 2,650,539 Greene Sept. 1,1953 

